5 results found.
... Science Frontiers ONLINE No. 55: Jan-Feb 1988 Issue Contents Other pages Home Page Science Frontiers Online All Issues This Issue Sourcebook Project Sourcebook Subjects Cyclothems as solar-system pulse recorders Geologists can help astronomers look back in time. The sunspot cycle can be seen in variations of varves; i.e ., annual layers of sediment; and the growth rings of shells have been used to estimate the number of days in the lunar month when the solar system was younger. Cyclothems may also be useful. Cyclothems are groups or bundles of strata that repeat themselves in stratigraphic columns. A generalized cyclothem from Illinois is shown in the illustration. In the U.S . western interior, rhythmic sedimentation appears in the Fort Hays Limestone Member of the Niobrara Formation. These cyclothems can be correlated over distances exceeding 800 kilometers and are believed to be the consequence of climatic changes associated with the earth's precession and orbital eccentriciy. These rhythms have been captured in bundles of shale-limestone couplets. A bundle of five coup lets, for example, is thought to express 21,000- and 100,000-year Milankovitchtype climatic cycles, as impressed by variations in the earth's orbital precession and eccentricity. Analysis of the Fort Hays Limestone Member, however, reveals that while bundles of five couplets do occur, the number may vary from 1 to 12. Clearly, things are not clear-cut. (Laferriere, Alan P., et al; "Effects of Climate, Tectonics, and Sea-Level Changes on Rhythmic Bedding Patterns in the Niobrara Formation ...
Terms matched: 1 - Score: 186 - 15 May 2017 - URL: /sf055/sf055p13.htm
... history. Indeed, all of the reference books confidently label charts with firm dates for the appearance of fishes, the demise of the dinosaurs, and so on. Alas, things are not quite as certain as they appear. Radiometric dating is not all that precise; errors may be large indeed. Take the Pennsylvanian period for example. It is part of the Carboniferous period, when many of the great coal deposits were laid down. The classical duration of the Pennsylvanian -- used in many texts -- is 34 million years. A meticulous new study of central European stratigraphy now pegs the Pennsylvanian as spanning only 19 million years. Now that's a 44% change! This new figure for the duration of the Pennsylvanian has already cast doubt on the origin of the famous Pennsylvanian cyclothems (repetitive strata) in North America. It had been thought that these seemingly cyclic deposits were correlated with sea level changes forced by variations in the earth's orbit (the Milankovitch periods). With this substantial compression of Pennsylvan-ian time, this correlation falls apart. The cyclothems, which are of impressive area and thickness, now seem to have been created by some other, still unrecognized phenomenon. (Klein, George deV.; "Pennsylvanian Time Scales and Cycle Periods," Geology , 18:455, 1990.) Comment. Even worse, perhaps, is the fuzziness conferred on the entire geological time scale by this compression of the Pennsylvanian and the possibility of similar revisions for other periods. From Science Frontiers #71, SEP-OCT 1990 . 1990- ...
Terms matched: 1 - Score: 25 - 15 May 2017 - URL: /sf071/sf071g11.htm
... Science Frontiers ONLINE No. 55: Jan-Feb 1988 Other pages Home Page Science Frontiers Online All Issues Last Issue Next Issue Sourcebook Project Sourcebook Subjects Contents Archaeology Archeological Stonewalling and Shadow Science Curious Sand-filled Cavities in the Great Pyramid Sardinia's Prehistoric Towers Demystifying Those Australian Craters Early Boomerang Astronomy An Astronomical Paradox Why Do Spiral Galaxies Stay That Way? Or Do They? Biology Migrating Birds Collide with Magnetic Bump The Scientific Basis of Astrology The Ubiquity of Sea Serpents A Glitch in the Evolution of Whales Geology Do We Really Understand the Dinosaurs? Cyclothems As Solar-system Pulse Recorders Geophysics Wheels of Light: Sea of Fire Powerful Concentric Waves The Zeitoun Luminous Phenomena Presumed Ball Lightning Things That Bo Buzz in the Night Psychology Psyching Out Piezoelectric Transducers Goethe's Optics Reevaluated ...
Terms matched: 1 - Score: 15 - 15 May 2017 - URL: /sf055/index.htm
... Rock Motion ESM12 Superficial Rocky Debris of Doubtful Provenance ESP ANOMALOUS PHYSICAL PHENOMENA IN GEOLOGY ESP1 Anomalous Radiohalos ESP2 Flexible Rocks ESP3 Unusually Colored Rocks ESP4 Noncrushing of Fossils in Sediment Compaction ESP5 Remarkable Polished Rocks ESP6 Ringing Rocks ESP7 Small-Scale Magnetic Anomalies ESP8 Frazil Ice, Anchor Ice,... ESP9 Long-Range Fine Structure In Strata ESP10 Jointing, Cleat, Crack Patterns ESP11 Shocked Mineral Grains at Geological Boundaries ESP12 Radiometric Dating Discordances ESP13 Natural Fission Reactors ESP14 Musical Sands ESP15 Luminous Rocks ESP16 Explosive Rocks ESP17 Dry Quicksand ESP18 Glacieres/Natural Refrigerators ESP19 Radioactive Fossils ESP20 Clustering of Mineralogical Dates in Time and Space ESP21 Random Cracking around Radioactive Inclusions ESR PHENOMENA OF THE OUTER CRUST ESR1 Incompleteness of the Stratigraphic Record ESR2 Lateral Variations in Strata ESR3 Apparently-Inverted Strata ESR4 Near-Global Unconformities ESR5 Rythmites and Cyclothems ESR6 Undisturbed and Unconsolidated Ancient Sediments ESR7 Vertical Stacking of Deposits ESR8 Continent-Type Rocks in the Ocean Depths ESR9 Exotic Terranes ESR10 Long Belts of Igneous and Metamorphic Rocks ESX PIERCEMENT STRUCTURES, INTRUSIVES, EXTERNAL IMPRESSIONS ESX1 Polystrate Fossils ESX2 Diapir Anomalies ESX3 Anomalies of Stigmaria ESX4 Perplexing Intrusives ESX5 Unusual Striations Attributed to Ice-Sheet Action ESX6 Anomalous Superficial Markings ET TOPOGRAPHIC ANOMALIES ETB BAYS, LAKES, SMALL DEPRESSIONS ETB1 Oriented Lakes and Depressions ETB2 Anomalous Features of Potholes ETB3 Fluid-Vent Craters ETB4 Gilgai Topography ETB5 Mountain-Top Depressions ETB6 Horseshoe-Shaped Depressions ETB7 Cookie-Cutter Holes ETB8 "Bottomless" Pits ETB9 Large Assemblages of Glacial Kettles ETB10 Depressions in Chalk Country ETC CRATERS, ASTROBLEMES, LARGE CIRCULAR STRUCTURES ETC1 Astroblemes (Starwounds) ETC2 Very Large Depressions of Probable Meteoric Origin ETC3 Hypothetical (and ...
Terms matched: 1 - Score: 14 - 15 May 2017 - URL: /cat-geol.htm
... author index, Subject index, references. 2006. ISBN 0-915554-62-3 . 7 x 10" format Geological Catalogs For a full list of geology subjects, see here . Inner Earth: A Search for Anomalies; A Catalog of Geological Anomalies Sorry, Out of print The focus of this, the eleventh volume in the Catalog of Anomalies, is the earth's interior, which is revealed to us mainly through seismic signals, magnetic variations, and the flow of heat from great depths. Hundreds of kilometers below the surface lurk huge pieces of foundered continental crust and bizarre structures of unknown origin. Typical subjects covered: Anomalous gravity signals * Mid-plate volcanism * Mysterious seismic reflectors * Seismic velocity discontinuities * Deep-focus earthquakes * Incompleteness of the stratgraphic record * Cyclothems and rhythmites * Exotic terranes * Compass anomalies * Earth-current anomalies * Problems of paleomagnetism * Polarity reversals [Picture caption: Model of the earth's interior] View Cart Buy online via PayPal with MC/Visa/Amex 230 pages, hardcover, $18.95, 52 illustrations, 5 indexes 1991, references, LC 90-92347, ISBN 915554-25-9 , 7x10 format. Carolina Bays, Mima Mounds, Submarine Canyons; A Catalog of Geological Anomalies Sorry, Out of print Topographical phenomena are the subject of this Catalog. The ups and downs of the earth's surface betray many anomalies. Could continental drift be inferior to the expanding earth hypothesis? Have ocean levels fluctuated wildly down the eons? Typical subjects covered: Carolina Bays and oriented lakes ...
Terms matched: 1 - Score: 6 - 10 Oct 2021 - URL: /sourcebk.htm
